Using double logistic equation to describe the growth of winter rapeseed

2018 ◽  
Vol 156 (1) ◽  
pp. 37-45 ◽  
Author(s):  
A. Shabani ◽  
A. R. Sepaskhah ◽  
A. A. Kamgar-Haghighi ◽  
T. Honar
Keyword(s):  
Growth Rate ◽  
Water Stress ◽  
Goodness Of Fit ◽  
Grain Filling ◽  
Maximum Growth ◽  
Logistic Function ◽  
Logistic Equation ◽  
Cold Period ◽  
Growth Stages ◽  
Winter Rapeseed

AbstractThere are many parameters in agriculture that change over time in a sigmoid pattern. In the current study, the double logistic function was used to describe and simulate dry matter (DM) variation of winter rapeseed plant and to explain the growth rate under water stress. Irrigation treatments were full irrigation at all growth stages, water stress during the vegetative stage in early spring, water stress at flowering and podding stages, water stress at grain filling stage and rain-fed treatment with supplemental irrigation at time of planting. A high value for the goodness of fit (0.996) and low value for normalized root mean square error (0.085) showed that the double logistic function can describe and simulate DM variation of rapeseed accurately. DM predicted by the double logistic equation based on growing degree day was slightly closer to the measured DM compared with the DM predicted by the double logistic equation based on days after planting. Results showed that growth rate before the winter cold period was lower than that after this period. There were two maximum growth rates for winter rapeseed: the first occurred before cold period and another after.

Effect of Limited Water Supply on Photosynthetic Characteristics of Spring Maize (Zea Mays)

2013 ◽  
Vol 404 ◽  
pp. 420-424
Author(s):  
Heng Jia Zhang ◽  
Jun Hui Li
Keyword(s):  
Growth Rate ◽  
Water Supply ◽  
Grain Filling ◽  
Growth Stages ◽  
Relative Growth ◽  
Crop Growth Rate ◽  
Leaf Stage ◽  
Spring Maize ◽  
Significant Difference ◽  
Leaf Area Duration

A trial was carried out to investigate the effect of limited water supply on leaf area duration (LAD), relative growth rate (RGR), crop growth rate (CGR), and above-ground biomass (AB) of spring maize. The results indicated that the LAD was significantly (p<0.05) increased by 10.6%, 15.4%, 16.9%, 19.3%, 13.4% and 17.0%,12.2%, 19.7%, 18.4%, 20.9% in MI1, MI3, MI4, MI5, CK than MI2 during both 12-leaf stage to heading and heading to silking. There was no significant difference (p>0.05) in RGR among all the treatments and check during 6-leaf to 12-leaf stage and silking to middle grain filling, but significant difference occurred during other measured stages. Also, significant difference was found in CGR among some treatments and check during all the measured growth stages. The maximum AB of maize was maintained in CK with 23.0 t ha-1, significantly improved by 16.2%, 16.2%, 22.3% and 41.1%, 35.3% respectively than in MI1, MI4, MI5 and MI2, MI3, and the minimum AB was recorded in MI2 with 16.3 t ha-1.

scholarly journals Growth of champa fruit under agroecological conditions of Miraflores, Boyacá, Colombia

2012 ◽  
Vol 47 (12) ◽  
pp. 1722-1730 ◽  
Author(s):  
Helber Enrique Balaguera-López ◽  
Aníbal Herrera Arévalo ◽  
Daniel Cortés-Moreno
Keyword(s):  
Growth Rate ◽  
Maximum Growth ◽  
Dry Mass ◽  
Exponential Model ◽  
Logistic Growth ◽  
Growth Stages ◽  
Fresh Matter ◽  
Absolute Growth ◽  
Fresh Pulp ◽  
Sigmoid Growth Curve

The objective of this work was to analyze the growth of champa fruit (Campomanesia lineatifolia) as a function of growing-degree days (GDD) in the municipality of Miraflores, in Boyacá, Colombia. Thirty trees were selected at random, and 100 flowers in full bloom were marked in each tree. From the 26th day after flowering until harvest, 10 samples were taken every 15 days to determine the fruit parameters and growth rate. Temperature was recorded to calculate the GDD. From flowering until harvest, 1,489.1 GDD were accumulated over 145 days. Dry and fresh matter mass of pulp, seed, and total fruit were fitted to a logistic growth model, and three growth stages (S1, S2 and S3) were defined. In the S1, growth was slow, and the relative growth remained nearly stable, whereas the absolute growth rate (AGR) increased slowly. In the S2, maximum growth was observed. In the S3, which corresponds to maturation, dry mass increased gradually, and the AGR decreased, while the fresh pulp and total mass did not cease to increase. The polar and equatorial diameters increased linearly, while the volume followed an exponential model. Champa fruit show a simple sigmoid growth curve.

Irrigation effects on quality characteristics of durum wheat

2003 ◽  
Vol 83 (2) ◽  
pp. 327-331 ◽  
Author(s):  
M. Güler
Keyword(s):  
Water Stress ◽  
Durum Wheat ◽  
Grain Filling ◽  
Quality Characteristics ◽  
Kernel Weight ◽  
Growth Stages ◽  
Key Words Wheat ◽  
Triticum Durum Desf ◽  
Irrigation Effects

Water stress can affect the quality characteristics of durum wheat (Triticum durum Desf.). The responses of three cultivars of durum wheat to four irrigation regimes [no irrigation or irrigation applied at three growth stages (sowing, jointing, and anthesis)] were evaluated at Ankara, Turkey, from 1993 to 1995. Thousand-kernel weight and test weight increased with irrigation at all three stages, whereas irrigation at sowing and jointing resulted in high pigmentation and protein values. When irrigation was applied at sowing and jointing, but not at anthesis, with water stress occurring only at grain filling, the quality of the grain was positively affected. Key words: Wheat, durum, stress, water quality, grain, irrigation

scholarly journals Rice Yield Components under Water Stress Imposed at Different Growth Stages

2018 ◽  
Vol 10 (3) ◽  
pp. 290
Author(s):  
Germani Concenço ◽  
José Maria Barbat Parfitt ◽  
Ivana Santos Moisinho ◽  
Marcos Valle Bueno ◽  
Jaqueline Trombetta da Silva ◽  
...  
Keyword(s):  
Water Stress ◽  
Yield Components ◽  
Rice Yield ◽  
Block Design ◽  
Grain Filling ◽  
Additional Treatment ◽  
Growth Stages ◽  
Rice Grain ◽  
Randomized Block Design ◽  
Four Levels

We aimed to assess rice yield components as function of water stress imposed at distinct crop growth stages under greenhouse, in randomized block design under factorial scheme 3 × 4 + 1, with four replications. The factor “A” was the growth stage in which water stress was imposed, being (a) vegetative, (b) reproductive 1, and (c) reproductive 2; factor “B” was four levels of water stress (0-200 kPa). There was also an additional treatment consisting of a flooded check. Water was replenished to saturation every time the threshold stress was reached. At the end of the cycle, all panicles were counted and collected, per plant, for further analysis. In the lab, grains per panicle were counted, being classified either as whole kernel or aborted grains, whose results were used for obtaining sterility percentage. Whole kernel grains were weighted for obtaining the 1000 grains weight for each treatment, and the consequent plant grain yields. Number of panicles was not affected when stress was imposed after panicle initiation, but when imposed at tillering it was reduced; at grain filling, water stress promoted grains sterility higher than 90%; grain weight was only reduced when carbohydrates were directed to root formation in detriment of grain filling; lower rice grain yield per plant was observed even when treatments were maintained above 10kPa all along the cycle, compared to the flooded treatment.

Effects of water stress on the physiological growth indices on performance of soybean genotypes

2015 ◽  
Vol 4 (2) ◽  
pp. 377-382
Author(s):  
Mustapha Yunusa ◽  
Alhassan Ibraheem ◽  
Manu Ibrahim
Keyword(s):  
Growth Rate ◽  
Water Stress ◽  
Leaf Area ◽  
Leaf Growth ◽  
Growth Stages ◽  
Matter Production ◽  
Factorial Trial ◽  
Soybean Genotypes ◽  
Net Assimilation ◽  
The University

Pot experiment was conducted at the Department of Agronomy Crop Pavilion of the University of Ilorin, Ilorinto assess the effects of water stress at different growth stages on the physiological parameters of soybean genotypes. Six soybean genotypes (TGX 536-02D, TGX 1830-2DE, TGX 1019-2EN, TGX 1740-2F, TGX 1485-1D and TGX 1817-12E) were subjected to water stress at three growth stages (vegetative, flowering and post-flowering stages) with a well-watered control. The experiment was designed as a factorial trial and laid out in split- plot arrangements. Morphological growth characters such as number of leaves, leaf area, branching and dry matter production were measured during growth which were used to determine physiological growth indices.Results show that crop growth rate (CGR), relative leaf growth rate (RLGR), net assimilation rate (NAR) and leaf area ratio measured at vegetative growth were significantly reduced by water stress occurring at the vegetative stage.Amongst the investigated genotypes TGX 536-02D was the most tolerant while 1485-1D was the least tolerant genotypes.

Describing and predicting potential growth in the pig

2004 ◽  
Vol 78 (3) ◽  
pp. 379-388 ◽  
Author(s):  
I. J. Wellock ◽  
G. C. Emmans ◽  
I. Kyriazakis
Keyword(s):  
Growth Rate ◽  
Goodness Of Fit ◽  
Growth Models ◽  
Growth Function ◽  
Logistic Function ◽  
Growth Data ◽  
Gompertz Function ◽  
Potential Growth ◽  
Nutritional Conditions ◽  
Wide Range

AbstractMost animal growth models contain an explicit growth function. It determines the pattern of growth over the lifetime of the animal and defines an upper limit to growth rate (the potential). The criterion of the ‘goodness-of-fit’ to one or more sets of data is frequently used to select a suitable growth function. Alternative criteria are described here that can be used to choose between forms that describe potential growth. Of the functions reviewed only a few fulfilled all of the proposed criteria. Of these the Logistic and Gompertz functions were favoured because of an economy of parameters and their ability to describe relative growth rate as a simple function of size. The Logistic function was rejected on the grounds of its numerical consequences for growth in pigs over a wide range of degrees of maturity, leaving the Gompertz function to be tested for its ability to make sensible predictions of potential growth. Pre-natal growth data, assumed to occur under non-limiting conditions as long as the mother is not subjected to extremely adverse nutritional conditions or incidence of infection, were used to estimate the values of the two Gompertz function parameters-the growth coefficient and the initial condition-given an estimate of mature size. The values were comparable with literature estimates based on post-natal growth and predictions of growth rate over a wide range of degree of maturity were thus sensible. On these grounds, and because it uses few parameters all with biological meaning, the Gompertz function is proposed as a suitable descriptor of potential growth.

scholarly journals Predicting Fermentation Rates in Ale, Lager and Whisky

Fermentation ◽  
2021 ◽  
Vol 7 (1) ◽  
pp. 13
Author(s):  
Struan J. Reid ◽  
Maria Josey ◽  
Andrew J. MacIntosh ◽  
Dawn L. Maskell ◽  
R. Alex Speers
Keyword(s):  
Logistic Model ◽  
Goodness Of Fit ◽  
Information Criterion ◽  
Logistic Function ◽  
Logistic Equation ◽  
Additional Parameter ◽  
Final Model ◽  
Industrial Fermentation ◽  
Scotch Whisky ◽  
Extra Parameter

Recently there has been an increased interest in characterising the rates of alcoholic fermentations. Sigmoidal models have been used to predict changes such as the rate of density decline. In this study, three published sigmoidal models were assessed and fit to industrial fermentation data. The first is the four-parameter logistic model described in the ASBC Yeast-14 method. The second model is a nested form of the four-parameter logistic function, adding an extra parameter, creating the 5-parameter logistic equation., where an additional parameter was added to allow for asymmetry. The final model is a three-parameter logistic equation which describes the change in the Apparent Degree of Fermentation with time. The three models were compared by fitting them to industrial data from Australian and Canadian lagers, American and Scottish ales and Scotch Whisky fermentations. The model fits were then compared to one another with a technique developed by Akaike and a nested F-test. The Akaike information criterion compares the models and accounts for both the goodness of fit, and the number of parameters in the model. Finally, consideration was given to the establishment of prediction bands (that enclose the area that one can be 99% sure contains the true datapoints). Calculation of these bands was “challenging” but successful as the industrial fermentation data was heteroscedastic.

Saturation mechanism and generated viscosity in gravito-turbulent accretion disks

2020 ◽  
Vol 640 ◽  
pp. A53
Author(s):  
L. Löhnert ◽  
S. Krätschmer ◽  
A. G. Peeters
Keyword(s):  
Growth Rate ◽  
Numerical Simulations ◽  
Accretion Disks ◽  
Gravitational Instability ◽  
Turbulent Viscosity ◽  
Radial Distance ◽  
Maximum Growth ◽  
Wave Number ◽  
Radiative Cooling ◽  
Mixing Length

Here, we address the turbulent dynamics of the gravitational instability in accretion disks, retaining both radiative cooling and irradiation. Due to radiative cooling, the disk is unstable for all values of the Toomre parameter, and an accurate estimate of the maximum growth rate is derived analytically. A detailed study of the turbulent spectra shows a rapid decay with an azimuthal wave number stronger than ky−3, whereas the spectrum is more broad in the radial direction and shows a scaling in the range kx−3 to kx−2. The radial component of the radial velocity profile consists of a superposition of shocks of different heights, and is similar to that found in Burgers’ turbulence. Assuming saturation occurs through nonlinear wave steepening leading to shock formation, we developed a mixing-length model in which the typical length scale is related to the average radial distance between shocks. Furthermore, since the numerical simulations show that linear drive is necessary in order to sustain turbulence, we used the growth rate of the most unstable mode to estimate the typical timescale. The mixing-length model that was obtained agrees well with numerical simulations. The model gives an analytic expression for the turbulent viscosity as a function of the Toomre parameter and cooling time. It predicts that relevant values of α = 10−3 can be obtained in disks that have a Toomre parameter as high as Q ≈ 10.

scholarly journals A global non-invasive methodology for the phenotyping of potato under water deficit conditions using imaging, physiological and molecular tools

Plant Methods ◽  
2021 ◽  
Vol 17 (1) ◽  
Author(s):  
M. Musse ◽  
G. Hajjar ◽  
N. Ali ◽  
B. Billiot ◽  
G. Joly ◽  
...  
Keyword(s):  
Water Stress ◽  
Water Deficit ◽  
Soil Conditions ◽  
Growth Stages ◽  
Dry Matter Content ◽  
Tuber Growth ◽  
Non Invasive ◽  
Potato Plants ◽  
Significant Difference

Abstract Background Drought is a major consequence of global heating that has negative impacts on agriculture. Potato is a drought-sensitive crop; tuber growth and dry matter content may both be impacted. Moreover, water deficit can induce physiological disorders such as glassy tubers and internal rust spots. The response of potato plants to drought is complex and can be affected by cultivar type, climatic and soil conditions, and the point at which water stress occurs during growth. The characterization of adaptive responses in plants presents a major phenotyping challenge. There is therefore a demand for the development of non-invasive analytical techniques to improve phenotyping. Results This project aimed to take advantage of innovative approaches in MRI, phenotyping and molecular biology to evaluate the effects of water stress on potato plants during growth. Plants were cultivated in pots under different water conditions. A control group of plants were cultivated under optimal water uptake conditions. Other groups were cultivated under mild and severe water deficiency conditions (40 and 20% of field capacity, respectively) applied at different tuber growth phases (initiation, filling). Water stress was evaluated by monitoring soil water potential. Two fully-equipped imaging cabinets were set up to characterize plant morphology using high definition color cameras (top and side views) and to measure plant stress using RGB cameras. The response of potato plants to water stress depended on the intensity and duration of the stress. Three-dimensional morphological images of the underground organs of potato plants in pots were recorded using a 1.5 T MRI scanner. A significant difference in growth kinetics was observed at the early growth stages between the control and stressed plants. Quantitative PCR analysis was carried out at molecular level on the expression patterns of selected drought-responsive genes. Variations in stress levels were seen to modulate ABA and drought-responsive ABA-dependent and ABA-independent genes. Conclusions This methodology, when applied to the phenotyping of potato under water deficit conditions, provides a quantitative analysis of leaves and tubers properties at microstructural and molecular levels. The approaches thus developed could therefore be effective in the multi-scale characterization of plant response to water stress, from organ development to gene expression.

scholarly journals Vegetation Response to Goats Grazing Intensity in Semiarid Hilly Grassland of the Loess Plateau, Lanzhou, China

2021 ◽  
Vol 13 (6) ◽  
pp. 3569
Author(s):  
Hua Cheng ◽  
Baocheng Jin ◽  
Kai Luo ◽  
Jiuying Pei ◽  
Xueli Zhang ◽  
...  
Keyword(s):  
Growth Rate ◽  
Community Structure ◽  
Plant Growth ◽  
Loess Plateau ◽  
Grazing Intensity ◽  
Gps Tracking ◽  
Growth Stages ◽  
The Loess Plateau ◽  
Vegetation Community ◽  
Natural Grasslands

Quantitatively estimating the grazing intensity (GI) effects on vegetation in semiarid hilly grassland of the Loess Plateau can help to develop safe utilization levels for natural grasslands, which is a necessity of maintaining livestock production and sustainable development of grasslands. Normalized difference vegetation index (NDVI), field vegetation data, and 181 days (one goat per day) of GPS tracking were combined to quantify the spatial pattern of GI, and its effects on the vegetation community structure. The spatial distribution of GI was uneven, with a mean value of 0.50 goats/ha, and 95% of the study area had less than 1.30 goats/ha. The areas with utilization rates of rangeland (July) lower than 45% and 20% made up about 95% and 60% of the study area, respectively. Grazing significantly reduced monthly aboveground biomass, but the grazing effects on plant growth rate were complex across the different plant growth stages. Grazing impaired plant growth in general, but the intermediate GI appeared to facilitate plant growth rate at the end of the growing seasons. Grazing had minimal relationship with vegetation community structure characteristics, though Importance Value of forbs increased with increasing GI. Flexibility in the number of goats and conservatively defining utilization rate, according to the inter-annual variation of utilization biomass, would be beneficial to achieve ecologically healthy and economically sustainable GI.

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